Cry it out can be traced back to 1894 in a book entitled, The Care and Feeding of Children written by Emmett Holt. Then, Dr. Richard Ferber’s book made the cry-it-out method popular in the 1980s. I don’t know about you, but I am not about listening to men who did their research before the 2000s happened…. That being said, any form of sleep training is likely to produce tears and crying, but that doesn’t mean they are crying it out. Crying is your child’s natural way of expressing themself when they do not yet have the availability of words.